Previous Year Question
With reference to bio-toilets used by the Indian Railways, consider the following statements:
The decomposition of human waste in the bio-toilets is initiated by a fungal inoculum.
Ammonia and water vapour are the only end products in this decomposition which are released into the atmosphere.
Which of the statements given above is/are correct?
1 only
2 only
Both 1 and 2
Neither 1 nor 2
Correct Answer: D
Detailed Solution
The bio-toilets of Indian Railways operate on the principle of anaerobic biological decomposition of human waste.
Indian Railways adopted this technology in collaboration with the Defence Research and Development Organisation.
A microbial consortium of anaerobic bacteria is used in the bio-digester tank of a bio-toilet.
These bacteria decompose complex organic matter present in human excreta in the absence of oxygen.
The decomposition process is not initiated by a fungal inoculum.
Anaerobic decomposition is generally completed through stages such as hydrolysis, acidogenesis, acetogenesis and methanogenesis.
During hydrolysis, complex organic matter is converted into simple soluble compounds.
In subsequent stages, these substances are converted into organic acids and other intermediate compounds.
Methanogenic microorganisms mainly produce methane and carbon dioxide from these compounds during the final stage.
The process also produces a liquid effluent that can be discharged after disinfection.
Therefore, ammonia and water vapour are not the only end products of this decomposition.
Bio-toilets were intended to prevent the direct discharge of human waste onto railway tracks.
They help reduce the problems of track corrosion, foul smell and unhygienic conditions.